Closed cranial window rodent model for investigating hemodynamic response to elevated intracranial pressure

Background:Elevated intracranial pressure(ICP)occurs in several physiological and pathological conditions,yet long-term sequellae are not common,which implies that blood flow is preserved above ischemic thresholds.Methods:This pilot study sought to confirm this hypothesis using a closed cranial window model in a rat in which ICP was elevated to 120 mmHg for 12 min,and superficial cortical perfusion was measured by laser Doppler flowmetry and laser speckle flowmetry.Results:Following a transient increase,cortical blood flow decreased to between 25%and 75%of baseline.These levels correspond to disrupted metabolism and decreased protein synthesis but did not exceed thresholds for electrical signaling or membrane integrity.This may partially explain how some episodes of elevated ICP remain benign.Conclusion:The closed cranial window model provides a platform for prospective study of physiologic responses to artificially elevated ICP during neurosurgery to promote hemostasis.

Wall shear stress in intracranial aneurysms and adjacent arteries

Hemodynamic parameters play an important role in aneurysm formation and growth. However, it is difficult to directly observe a rapidly growing de novo aneurysm in a patient. To investigate possible associations between hemodynamic parameters and the formation and growth of intracranial aneurysms, the present study constructed a computational model of a case with an internal carotid artery aneurysm and an anterior communicating artery aneurysm, based on the CT angiography findings of a patient. To simulate the formation of the anterior communicating artery aneurysm and the growth of the internal carotid artery aneurysm, we then constructed a model that virtually removed the anterior communicating artery aneurysm, and a further two models that also progressively decreased the size of the internal carotid artery aneurysm. Computational simulations of the fluid dynamics of the four models were performed under pulsatile flow conditions, and wall shear stress was compared among the different models. In the three aneurysm growth models, increasing size of the aneurysm was associated with an increased area of low wall shear stress, a significant decrease in wall shear stress at the dome of the aneurysm, and a significant change in the wall shear stress of the parent artery. The wall shear stress of the anterior communicating artery remained low, and was significantly lower than the wall shear stress at the bifurcation of the internal carotid artery or the bifurcation of the middle cerebral artery. After formation of the anterior communicating artery aneurysm, the wall shear stress at the dome of the internal carotid artery aneurysm increased significantly, and the wall shear stress in the upstream arteries also changed significantly. These findings indicate that low wall shear stress may be associated with the initiation and growth of aneurysms, and that aneurysm formation and growth may influence hemodynamic parameters in the local and adjacent arteries.

Computational fluid dynamics modeling in intracranial atherosclerotic disease

Intracranial atherosclerotic disease(ICAD)is an important cause for ischemic stroke and transient ischemic stroke(TIA)throughout the world,especially in Asians,which is not fully appreciated,partly due to its inaccessibility and limitations of current neuroimaging methods.The computational fluid dynamics(CFD)modeling technique provides a novel approach to reveal the hemodynamic characteristics in ICAD,e.g.,the distributions of pressure,wall shear stress and flow velocity.In this review article,we aim to provide an overview of the general methodology of CFD modeling in arterial stenotic diseases,the established application of this technique in coronary artery disease,and more importantly,perspectives and challenges of this technique in the investigation of ICAD.Promising findings of preliminary studies using a CFD model for hemodynamic analysis in ICAD warrant verifications.Further studies in this area will help rectify loopholes in the current secondary prevention strategy,and inform individualized treatment for ICAD patients in the near future.

单纯放置LVIS支架治疗颅内动脉瘤的初步经验

目的 探讨单纯使用LVIS支架治疗颅内动脉瘤(IA)的有效性和安全性。方法 回顾性收集采取单纯LVIS支架治疗的45例患者临床资料,对IA的特征及影像学随访结果进行分析。结果 45例患者通过单纯放置LVIS支架共治疗48个IA。术后4~24个月接受脑血管造影复查,中位复查时间7个月。Raymond分级Ⅰ级的IA 31个,Ⅱ级4个,Ⅲ级13个,总体治愈率64.58%。单LVIS支架治疗30个IA,治愈率56.67%,双LVIS支架套叠治疗18个IA,治愈率77.78%。所有患者获得出院6个月时的门诊或电话随访,均未发生严重缺血或出血事件。改良Rankin量表评分(mRS)均为0~2分。结论 单纯放置LVIS支架治疗IA安全可行,但治愈率低于其辅助弹簧圈栓塞,不宜作为IA的首选治疗方案。对于术中无法填塞弹簧圈或术前不接受血流导向装置以及开颅夹闭术治疗的患者,双LVIS支架治疗可作为备选方案或术中补救措施。

脑动脉粥样硬化性狭窄患者合并颅内动脉瘤的血流动力学特征及其危险因素研究

目的探讨脑动脉粥样硬化性狭窄患者合并颅内动脉瘤(IA)的血流动力学特征及其危险因素。方法收集2019年9月至2023年1月在安徽医科大学附属宿州医院接受治疗的160例脑动脉粥样硬化性狭窄患者的临床资料。所有患者均进行了CT血管成像(CTA)以及数字减影血管造影(DSA)检查,依据影像学检查结果分为合并IA组(25例)和单纯狭窄组(135例)。比较2组基线资料信息、血流动力学指标。采用多因素Logistic回归分析探讨脑动脉粥样硬化性狭窄患者合并IA的危险因素。通过受试者操作特征(ROC)曲线分析壁面切应力(WSS)及振荡切应指数(OSI)预测脑动脉粥样硬化性狭窄患者合并IA的价值。结果合并IA组WSS、OSI均明显高于单纯狭窄组(P<0.05)。合并IA组中有吸烟史、糖尿病、高血压的百分比均高于单纯狭窄组(P<0.05)。多因素Logistic回归分析显示,吸烟史、糖尿病、高血压、WSS>0.450 Pa、OSI>0.057是脑动脉粥样硬化性狭窄患者合并IA的危险因素(P<0.05)。ROC曲线分析显示,WSS、OSI可用于预测脑动脉粥样硬化性狭窄患者合并IA,曲线下面积分别为0.857、0.784,敏感度分别为0.681、0.859,特异度分别为0.751、0.771(P<0.05)。结论脑动脉粥样硬化性狭窄患者合并IA的危险因素包括吸烟史、糖尿病、高血压、WSS>0.450 Pa、OSI>0.057。WSS、OSI可用于预测脑动脉粥样硬化性狭窄患者合并IA。

基于多孔阶跃面技术的颅内动脉瘤数值模拟方法研究

目的 研究基于多孔阶跃面技术模拟构建的血流导向装置(FD)在颅内动脉瘤数值模拟方面的可行性及可靠性,为临床治疗颅内动脉瘤在支架选择方面提供理论支持。方法 纳入兰州大学第二医院神经外科一例颅内动脉瘤患者动脉瘤体数字减影血管造影(DSA)造影图像数据,通过Mimics等软件构建其基本几何模型并进行FD模型的置入,再进一步对所建模型进行网格划分和求解计算,以获得该模型血流动力学指标分布情况。结果 观测血流动力学指标,与置入前比较,发现模拟置入FD后动脉瘤体整体压力显著下降;瘤体平均壁面剪切力(WSS)整体下降,且动脉瘤体高WSS区域明显减少;另外FD置入对动脉瘤内部的涡量产生有较大影响,极大地降低了动脉瘤瘤体内部的血液流动速度。结论 对比既往大量研究数据,发现通过多孔阶跃面技术进行数值模拟所得结果与其保持一致,提示本研究方法行之有效,且较之其他方法更加快速、准确,在临床诊疗活动中有较大的应用前景。

钙通道阻滞剂对未破裂颅内动脉瘤影响的研究进展

未破裂的颅内动脉瘤是一颗埋在患者体内的定时炸弹,这类患者往往伴有高血压病。除去多数研究已证实的促破裂危险因素以外,复杂的血流动力学、炎症因素以及未控制的高血压也增加了其破裂风险。作为临床常用的抗高血压药物,钙通道阻滞剂被发现在促破裂进程中可以发挥保护作用,但也有研究发现了不同甚至矛盾的结果。本文就动脉瘤破裂的危险因素、钙通道阻滞剂使用对瘤体破裂的影响以及发挥的双重效应作一综述。

脑动脉瘤术后经法舒地尔联合尼莫地平使用对脑血管痉挛的预防效果研究

目的 探讨脑动脉瘤术后经法舒地尔联合尼莫地平使用对脑血管痉挛的预防效果。方法 选取2021年1月至2022年12月收治的80例脑动脉瘤患者,各患者均接受血管内介入栓塞术治疗,用随机数字表法将其分对照组和观察组,各40例,对照组接受尼莫地平治疗,观察组术后接受法舒地尔联合尼莫地平治疗,比较两组治疗状况。结果 观察组治疗疗效97.50%高于对照组75.00%(P <0.05);观察组治疗后MMSE评分、NIHSS评分优于对照组(P <0.05);观察组治疗后RI低于对照组,PI、Vm、MPV高于对照组(P <0.05)。结论 脑动脉瘤术后接受法舒地尔联合尼莫地平治疗,可加大脑部血流速度,改善神经功能,疗效理想。

喉罩吸入麻醉联合舒更葡糖钠对颅内动脉瘤介入栓塞术患者血流动力学和苏醒质量的影响

目的:观察并探讨颅内动脉瘤介入栓塞术患者经喉罩吸入麻醉与舒更葡糖钠联合应用效果,以及对血流动力学、苏醒质量的影响。方法:前瞻性选取佳木斯市中心医院于2021年1月—2022年12月接收的87例颅内动脉瘤介入栓塞术患者作为研究对象,随机分为对照组(n=45)、观察组(n=42),对照组给予喉罩吸入麻醉联合新斯的明,观察组给予喉罩吸入麻醉联合舒更葡糖钠。比较两组血流动力学、苏醒质量、肌松残余率、不良反应。结果:两组用药前血流动力学比较差异均无统计学意义(P>0.05);用药后1、5、15、30 min,对照组心率、呼吸、平均动脉压均升高,观察组心率、呼吸、平均动脉压无明显变化;用药后1、5、15、30 min,观察组心率、呼吸、平均动脉压均比对照组低,差异均有统计学意义(P<0.05)。观察组拔罩时间、自主呼吸恢复时间、意识清醒时间均早于对照组,住院时间短于对照组,差异均有统计学意义(P<0.05)。观察组用药后10、20、30 min肌松残余率均低于对照组,差异均有统计学意义(P<0.05)。观察组术后咳嗽、呼吸抑制、干呕、疼痛等不良反应总发生率低于对照组,差异有统计学意义(P<0.05)。结论:喉罩吸入麻醉与舒更葡糖钠联合应用于颅内动脉瘤介入栓塞术患者中,能够稳定血流动力学,提高患者术后苏醒质量,减少肌松残余,保障患者治疗安全。

尼莫地平联合常规疗法治疗颅脑损伤的临床效果分析

目的:分析尼莫地平联合常规疗法治疗颅脑损伤的临床效果。方法:选取2021年9月—2022年8月湘潭县人民医院急诊ICU收治的62例颅脑损伤患者作为研究对象,以随机数字表法分为研究组与对照组,各31例。对照组采用常规治疗,研究组在对照组基础上采用尼莫地平治疗。比较两组治疗效果。结果:治疗2、3 d后,两组脑组织氧分压高于治疗前,且研究组高于对照组,差异有统计学意义(P<0.05)。治疗3、7 d后,两组颅内压低于治疗前,且研究组低于对照组,差异有统计学意义(P<0.05)。治疗7 d后,两组动态血管阻力、脑血管阻力低于治疗前,且研究组低于对照组,两组平均血流量、伤侧颈动脉平均血流速度高于治疗前,且研究组高于对照组,差异有统计学意义(P<0.05)。研究组治疗总有效率高于对照组,差异有统计学意义(P=0.044)。结论:尼莫地平联合常规疗法治疗颅脑损伤的临床效果较好,能够改善患者脑组织氧分压、血流动力学参数,降低颅内压。

The effect of aneurismal-wall mechanical properties on patient-specific hemodynamic simulations:two clinical case reports

Hemodynamic factors such as the wall shear stress play an important role in the pathogenesis and treatment of cerebral aneurysms. In present study, we apply computational fluid-structure interaction analyses on cerebral aneurysms with two different constitutive relations for aneurismal wall in order to investigate the effect of the aneurismal wall mechanical properties on the simulation results. We carry out these analyses by using two patient-specific models of cerebral aneurysms of different sizes located in different branches of the circle of Willis. The models are constructed from 3D rotational angiography image data and blood flow dynamics is studied under physiologically representative waveform of inflow. From the patient models analyzed in this investigation, we find that the deformations of cerebral aneurysms are very small. But due to the nonlinear character of the Navier-Stokes equations, these small deformations could have significant influences on the flow characteristics. In addition, we find that the aneurismal-wall mechanical properties have great effects on the deformation distribution of the aneurysm, which also affects the wall shear stress distribution and flow patterns. Therefore, how to define a proper constitutive relation for aneurismal wall should be considered carefully in the hemodynamic simulation.

Importance of incorporating systemic cerebroarterial hemodynamics into computational modeling of blood flow in intracranial aneurysm

The importance of properly treating boundary conditions (BCs) in numerical simulation of hemodynamics in intracranial aneurysm (IA) has been increasingly recognized. In this study, we constructed three types of computational model for each IA to investigate how the outcome of numerical simulation is affected by the treatment of BCs. The first type of model (i.e., Type-A model) was obtained by applying 3-D hemodynamic modeling to the entire cerebral arterial network, with its solution being taken as the reference for evaluating the performance of the other two types of model (i.e., Type-B and Type-C models) in which 3-D modeling was confined to the aneurysm region. In addition, patient-specific 1-D models of the cerebral arterial network were developed to provide hemodynamic information for setting the inflow/outflow BCs of the 3-D models. Numerical tests on three IAs revealed that prescribing the outflow BCs of a localized 3-D aneurysm model based on 1-D model-simulated outflow division (i.e., Type-B model) instead of imposing the free outflow BC on all outlets (i.e., Type-C model) helped to improve the fidelity of the simulation of intra-aneurysmal hemodynamics, but could not guarantee a complete reproduction of the reference solution obtained by the Type-A model. Moreover, it was found that the outcome of hemodynamic simulation was more sensitive to the treatment of BCs when an aneurysm was located at arterial bifurcation rather than sidewall. These findings highlight the importance of taking into account systemic cerebroarterial hemodynamics in computational modeling of hemodynamics in IAs, especially those located at bifurcations.

Underlying mechanism of hemodynamics and intracranial aneurysm

In modern society,subarachnoid hemorrhage,mostly caused by intracranial aneurysm rupture,is accompanied by high disability and mortality rate,which has become a major threat to human health.Till now,the etiology of intracranial aneurysm has not been entirely clarified.In recent years,more and more studies focus on the relationship between hemodynamics and intracranial aneurysm.Under the physiological condition,the mechanical force produced by the stable blood flow in the blood vessels keeps balance with the structure of the blood vessels.When the blood vessels are stimulated by the continuous abnormal blood flow,the functional structure of the blood vessels changes,which becomes the pathophysiological basis of the inflammation and atherosclerosis of the blood vessels and further promotes the occurrence and development of the intracranial aneurysm.This review will focus on the relationship between hemodynamics and intracranial aneurysms,will discuss the mechanism of occurrence and development of intracranial aneurysms,and will provide a new perspective for the research and treatment of intracranial aneurysms.

Hemodynamics,inflammation,vascular remodeling,and the development and rupture of intracranial aneurysms:a review

The central nervous system is an immunologically active environment where several components of the immune and inflammatory response interact among them and with the constituents of nervous tissue and vasculature in a critically orchestrated manner,influencing physiologic and pathologic processes.In particular,inflammation takes a central role in the pathogenesis of intracranial aneurysms(IAs).The common pathway for aneurysm formation involves endothelial dysfunction and injury,a mounting inflammatory response,vascular smooth muscle cells(VSMCs)phenotypic modulation,extracellular matrix remodeling,and subsequent cell death and vessel wall degeneration.We conducted a literature review(1980-2014)by Medline and EMBASE databases using the searching terms“IA”and“cerebral aneurysm”and further search was performed to link the search terms with the following key words:inflammation,hemodynamic(s),remodeling,macrophages,neutrophils,lymphocytes,complement,VSMCs,mast cells,cytokines,and inflammatory biomarkers.The aim of this review was to summarize the most recent and pertinent evidences regarding the articulated processes of aneurysms formation,growth,and rupture.Knowledge of these processes may guide the diagnosis and treatment of these vascular malformations,the most common cause of subarachnoid hemorrhage,which prognosis remains dismal.

计算流体力学在颅内动脉瘤仿真建模及破裂风险预测中应用的研究进展

颅内动脉瘤是一种以动脉壁局部扩张为特征的脑血管疾病。颅内动脉瘤破裂导致的蛛网膜下腔出血具有较高的病死率和致残率。近年来,通过计算流体力学的方法开展的血流动力学参数与颅内动脉瘤破裂风险相关性研究取得较大进展,但目前仍存在一定的争议。作者就计算流体力学在颅内动脉瘤仿真建模及破裂风险预测中应用的研究进展进行了综述。

尺寸比及子囊形成对颅内镜像动脉瘤破裂的影响

目的探讨颅内镜像动脉瘤的形态学及血流动力学特征及其对动脉瘤破裂的影响。方法回顾性分析颅内镜像动脉瘤46例92枚动脉瘤的数字减影血管造影资料,采用计算流体动力学模拟。收集动脉瘤15个形态学参数和5个血流动力学参数。比较破裂动脉瘤与未破裂动脉瘤各参数的差异,采用多因素Logistic回归分析法确定动脉瘤破裂的危险因素。采用受试者工作特征(receiver operating characteristic,ROC)曲线分析各参数预测动脉瘤破裂的曲线下面积(area under curve,AUC)和阈值。结果破裂组动脉瘤形状不规则、子囊形成发生率多于未破裂组,最大径、高度、宽度、最大深度、瓶颈因子(bottle neck factor,BNF)、纵横比(aspect ratio,AR)、尺寸比(size ratio,SR)、高宽比(height/width,H/W)、深宽比(Hmax/width,Hmax/W)大于未破裂组,平均壁面剪切力、标准化壁面剪切力小于未破裂组,差异有统计学意义(P<0.05);2组位于分叉部、瘤颈宽度、载瘤动脉直径(diameter of parent vessel,DV)、流入角、最大壁面剪切力、平均震荡剪切指数、载瘤动脉壁面剪切力差异无统计学意义(P>0.05)。多因素Logistic回归分析结果显示,SR和子囊形成是动脉瘤发生破裂的危险因素。ROC分析结果显示,最大径、高度、最大深度和SR具有较高的AUC值分别为0.841、0.820、0.847和0.873。结论破裂的颅内镜像动脉瘤更多见于不规则形态与子囊形成的动脉瘤,并具有较大的最大径、高度、宽度、最大深度、AR、SR、H/W、Hmax/W与较小的平均壁面剪切力、标准化壁面剪切力,其中SR及子囊形成是颅内镜像动脉瘤破裂的危险因素。

CT灌注成像评估颅脑损伤的程度及其对ICP探头置入术后脑血流动力学的预测价值

[目的]探讨CT灌注成像评估颅脑损伤的程度及其对ICP探头置入术后脑血流动力学的预测价值.[方法]选择2016年1月至2020年12月本院收治的79例颅脑损伤患者(观察组),其中轻度患者25例,中度患者21例,重度患者33例.另选取同期进行健康体检者79例(对照组).比较观察组及对照组、不同严重程度颅脑损伤患者、不同疗效患者局部脑血流量(rCBF)、局部脑血容积(rCBV)、血液通过组织的平均时间(MTT).受试者工作特征(ROC)曲线分析rCBF、rCBV、MTT检测对颅脑损伤的严重程度以及治疗效果的预测价值.[结果]观察组rCBF、rCBV显著低于对照组,MTT显著高于对照组,差异有统计学意义(P<0.05).轻度组、中度组、重度组rCBF、rCBV呈逐渐下降的趋势,MTT呈升高趋势,且组间比较差异有统计学意义(P<0.05).有效组患者rCBF、rCBV高于无效组,MTT低于无效组,差异有统计学意义(P<0.05).ROC曲线分析显示,rCBF、rCBV、MTT联合检测对颅脑损伤的严重程度以及治疗效果的预测曲线下面积显著高于单独检测(P<0.05).[结论]CT灌注成像对脑损伤程度的诊断及其对ICP探头置入术后脑血流动力学的诊断特异度较高,值得临床推广应用.

形态学和血流动力学因素预测颅内动脉瘤破裂风险的研究进展

颅内动脉瘤(IA)通常指颅内动脉血管壁上的局限性囊性膨出,多见于颅内前循环的Willis环。动脉瘤一旦破裂可导致蛛网膜下腔出血,因此具有较高的病死率和长期致残率。临床影响IA破裂的风险因素较多,其中形态学和血流动力学已成为目前IA相关研究领域的热点。因此,未来进一步明确各风险因素与动脉瘤破裂的关系、制订破裂风险评估量表评估动脉瘤的破裂风险以及最佳治疗策略,可以为疾病的治疗提供新思路。

Biological characteristics of the cerebral venous system and its hemodynamic response to intracranial hypertension

Background The role of the cerebral venous system （CVS） in intracranial pressure （ICP） regulation remains largely unclear. In the present study, the interaction between ICP and the cerebral venous system and its possible mechanism were investigated with respect to the biological characteristics of the cerebral venous system and its hemodynamic response under increased ICP. Methods We created intracranial hypertension animal model, measured and calculated the venous flow velocity and diameter of the outflow terminal of the CVS with color ultrasonic system and recorded the vascular morphology by 3-dimensional anatomical microscopy. Patients who suffered from raised ICP underwent MRI and digital subtraction angiography （DSA） examination to show the length in the vertical direction of the wall of the bridging vein representing the diameter value. Pathological autopsy was performed from bodies of patients who had died from non-cerebral causes to observe the juncture part between the venous sinuses and tributary vertical brain veins. Results Under increased ICP conditions, venous drainage through the outlet cuff segment, a unique structure between the bridge vein and sinus, was obstructed and in turn venous blood became congested. Therefore, the increased blood volume worsened the pre-existing ICP according to the well-accepted theory regarding volume-pressure relationship. This phenomenon was described as concurrent ＇k, enogenic intracranial hypertension＂, which is characterized by intracranial venous blood stasis responsive to and together with the original increased ICP. Conclusions The existence of this special pathophysiological process is prevalent, rather than rare, in various intracraniAI disorders. Thi.~ findinn would definitAIv nrovide new insinht into the. Area of cerebral venous svstem research.

颈动脉超声联合眼动脉超声对颈内动脉颅内段病变的定位诊断价值

目的探讨颈动脉多普勒超声(CDU)联合眼动脉(OA)超声评估颈内动脉(ICA)颅内段重度狭窄或闭塞位置的应用价值。方法回顾性收集经数字减影血管造影(DSA)证实为单侧ICA颅内段重度狭窄或闭塞病人(病变组)97例及ICA颅内段无明显狭窄对照者(对照组)85例,根据病变程度和位置将病变组病人进一步分为重度狭窄OA分支前组(30例)、重度狭窄OA分支后组(21例)、闭塞OA分支前组(28例)、闭塞OA分支后组(18例)。所有病人均行超声检查测量ICA颅外段及OA的血流动力学参数。采用单因素方差分析比较各组间ICA颅外段和OA的血流动力学参数的差异,进一步两两比较采用LSD-t检验;采用受试者操作特征(ROC)曲线分析ICA颅外段和OA血流动力学参数对ICA颅内段病变位置的诊断效能。结果重度狭窄病人和闭塞病人的OA分支前组、OA分支后组的患侧ICA颅外段收缩期峰值流速(PSV)、舒张末期流速(EDV)均低于对照组,阻力指数(RI)高于对照组,OA分支前组的患侧EDV高于OA分支后组及对照组,搏动指数(PI)低于OA分支后组及对照组(均P<0.05)。ROC曲线分析显示,重度狭窄病人双侧OA的PI变异度、闭塞病人患侧ICA颅外段RI和双侧OA的PI变异度对于判定ICA颅内段病变位置具有较好的诊断效能。结论联合分析ICA颅外段和OA血流动力学参数,可以有效确定ICA颅内段重度狭窄或闭塞的病变位置。